CSS is just some lines of static code. There is nothing dynamic in CSS. To extend the productivity many CSS developers have developed many extensions for it. CSS preprocessors are a part of it. And LESS is one of them.

While we develop dynamic web applications we query data for dynamically generated pages by any unique value ( like ID, Product Code, Slug) of that page.

In our dynamic web applications we define URLs in which we specify some parameters like ID, slug, code or anything unique to get the specified object. But if that URL cannot get any object then it will show an error which can reveal some sensitive informations of your web application.